A full-time national serviceman who knifed four women in 2010, killing a mother of two, was sentenced to life imprisonment on Thursday. Soh Wee Kian, 23, stood expressionless in the dock as he heard his sentence.

Prosecutors had asked for a life term for Soh, who loitered around housing estates with a knife in his pocket, trailing women with long hair and in short skirts. As he followed them, he fantasised about stabbing them in the back, kissing them and touching their breasts.

Soh's defence lawyers did not oppose the prosecution's request for a life sentence. They asked the court not to cane Soh on grounds that he had a mental impairment. Prosecution psychiatrist Jerome Goh said Soh suffered from an adjustment order while defence psychiatrist Tommy Tan diagnosed Soh to be suffering from schizotypal disorder.

The prosecution did not accept Dr Tan's diagnosis, but said it was not asking for caning to be imposed.